Compositing output image shading
Cycles:
Shadeless image:
You can do this in cycles by enabling the Color passes in Renderlayers &gt; Passes:

Then add them together in the compositor with Mix nodes:

Original image:

Post composite:

Shading only:
You can get only the shading of the render by dividing the full render and the color pass:

The reason the large cube appears as if it is still textured is that it has a Glass material, so that is the shading result. To prove this we can multiply it back with the color pass and we will get the full render again:

Blender internal:
You could get a &quot;shadeless&quot; pass in BI with the Color pass in Renderlayers &gt; Passes:

Result:

Saving multiple images from the compositor:
You could then save the shadeless images in a separate directory with the File output node:

Note that the output connected to the composite output node will be saved to the path specified Render settings &gt; Output. In the absence of a Composite  node, the raw render will be saved.
The above node setup the raw render is saved to the path in Render settings &gt; Output (in this case /tmp/) and the shadeless image is saved to /tmp/shadeless/.